Polyethylene terephthalate or “PET” polymers and co-polymers are widely used to manufacture bottles for beverages such as water, juices, carbonated soft drinks (CSD), and the like, because they generally possess good mechanical and gas barrier properties. Over this time, container designs have been improved and optimized for increasingly lighter weights and affordability. Such bottles are conventionally prepared using a stretch blow molding process. Stretch blow molding first involves injecting the PET resin into a preform injection mold designed according to the desired final bottle shape and size and the PET polymer properties. The preform is subsequently stretch blow molded in which the heated preform is both blown and stretched into the final container shape using compressed air and an axial stretching rod.
One significant feature in container design as it relates to CSD bottle performance, mechanical properties, and the stretch blow molding process, for example, is the design of the bottle base. Base design has been found to influence to a substantial degree, for example, the ability to successfully light weight a bottle. Base design also influences bottle performance such as stress crack performance, and other features. Base design can also improve the desired physical robustness of the bottle, and enhance processing features such as the maintenance of bottle integrity during the stretch blow molding process.
Therefore, improved bottle and base designs are needed that also enable improved light weighting and which allow light weighted bottles to achieve good stress crack performance, and good drop failure performance, and other features. Base designs that can improve generally the desired physical robustness of the bottle, regardless of its size, and enhance processing features when used with various PET resin compositions are also of interest. It would be preferable if such new bottle designs and methods also could be applicable to a variety of container polymers such as nylons and nylon blends, in addition to PET resin containers.